Is it not the case that cover versions are an example of a familiar process in many genres, whereby songs and tunes develop, mutate and transform themselves? and is there really any particular reason why this process should be especially succesful in jazz? On this final point, the argument would be that jazz is especially suited to song development, because a key (even defining) component of jazz is improvisation. However, improvisation is not exclusive to jazz, and occurs frequently in other genres. Let me give a concrete example. A few months ago, Charlie played "Candyman" by Mississippi John Hurt. Rev Gary Davis also has a version of this; but there is very little similarity between the two; they only share the same title and bawdy subject matter (I'm surprised that Charlie played this before the "family threshold" of 9pm without losing his contract). No doubt, in the distant past, the same material somehow mutated into these two different songs. But Rev Davis made a "Candyman" of his own; he had different versions for various dance steps, and it is known that he would play the song for hours on end at dances, without repetition, continually improvising on a fairly simple tune. I am not aware of any recording of this of this length, but there are other lengthy recordings of his (eg Walkin' Dog Blues), that show his kind of improvisation. Of course, I have no way of knowing for sure, but I bet that the master ragtime guitarist Blind Blake did the same long improvisations in this genre. Surely, what is shared with John Coltrane is that these were all virtuoso musicians, not necessarily prodigies, who worked, practised and performed incredibly hard, and this is what turned scant material into magic. To me, what is interesting about "My Favourite Things" is the process, over some forty years, where it is widely appreciated by people, who would not normally listen to jazz. I know this is anecdotal, but it now seems to feature on "Desert Island Discs". But, I wonder whether this might happen in other genres, where there is virtuosity and improvisation. Who knows, but maybe in forty years time, a bluegrass version of a trite pop song may "burst out of the genre", and gain the recognition of John Coltrane's great piece. Incidentally, I have not deliberately excluded World Music here - I simply do not have the knowledge that is so abundant on this site.

If ever there was a time for Charlie to play Elvis Costello, this must be it, for his 'This is Hell' contains a great line about the song that keeps occurring in this thread, as he describes one of his visions of Purgatory:- "My Favourite Things is playing again and again/But it's by Julie Andrews and not by John Coltrane".

Please Don't Let Me Be Misunderstood Con!
By saying "musical incompetence" I was being ironic.

I'm probably almost as much a Costello fan as you are, and respect the man for coming clean in such a straight forward and demystifying manner, about one of his song writing methods.
Though I can't show you the quote I can assure you the gist of what I have reported is correct. It stuck with me because as an (ex)songwriter myself I have always been fascinated by other writers methods.

Obviously Elvis didn't slavishly copy other songs but it was in an attempt to get there style, or their magic, that he would deconstruct them, and as a result of not nailing their essence perfectly, would end up with a Costello song. You say:

"Get Happy!! was soul songs deconstructed then his own songs built on top."

- I'm not sure what the difference between this and what I said is?

And another thing. I would imagine 98% of popular songwriters post Beatles can't write music. Writing a song without being able to read music hardly takes a genius, it just takes a multitrack tape recorder and an ear for a good tune. But once again, I'n not saying Costello isn't a genius, just making an observation.

PS

'This is Hell' did cross my mind when I was writing about the Coltrane cover.

David Godwin wrote:But, I wonder whether this might happen in other genres, where there is virtuosity and improvisation.

David, I don't think virtuosity is the key. Isn't it more like the musician-as-fan when, regardless of their own talent level, the cover version somehow manages to express the essence of something in the original song that we haven't (consciously) seen ourselves?

Another, perhaps almost too obvious to mention or think of, factor, is the artist as fan and relatively inexperienced musician. In fact the very opposite end of the cover version spectrum, to David's analysis of Jazz's contribution.
Jazz musicians seemed to feel compelled to take the bold Pop Art poster of a pop song and turn it into a gigantic, complex tapestry.
A young band picking up their insruments for the first time just needed some place to start.

The Jazz cover is a drop in the ocean compared to the millions of cover versions in the world which must have been done by bands when they were just trying to find their feet. We don't have to look any further than two of the biggest - The Beatles and The Stones. Correct me if I'm wrong, but don't covers outnumber originals on their first couple of albums?

This is the cover being used as an aid to learning an instrument and learning to write a song. For the intuitive rather than classically trained musician, this was the only way to master your instrument - you either played along to the record or, by the time I was learning, bought a book of your favourite band's songs and followed the chord diagrams.

Chord diagrams were a Godsend to the musician who had neither the time or attention span to learn to read music, because in essence, they were simply pictures of where to put your fingers: six horizontal lines for the strings, three vertical: for the frets. And little black dots for where you put your confused, stupid fingers. There was nothing academic or distancing about them. Within a couple of weeks your fingers stopped feeling like bananas, and you would be playing a favourite pop tune, providing it stayed to typical pop tune chords such as the obvious A, E and D.

Perhaps someone out there knows when the chord diagram was invented?

But anyway, to get back on track - the cover version was the way in. A band or artist could pay homage to whoever had inspired them in the first place, whilst at the same time learning their craft. In fact, was it the Stones or Beatles (or both) that actually had to be persuaded by management to pull their finger out and get down to producing some of their own material, because that was where the money was?

Anyone going to Sterns this afternoon to see Nuru? Might see you there!

Interesting point about the Stones and Beatles debuts. The Pogues also had more covers than originals on their debut album. Not that I'm comparing Messrs MacGowan and Finer to Jagger, Richards, Whatsisname and McSomethingOrOther, but there's something in that idea of starting out by largely covering others' material. Maybe I should revise my snobbery about 'tribute' bands. Some of those guys might just be taking the first step to greatness. :-)

You forgot to put your little smiley symbol after that last comment Con. But I trust you were joking. The tribute band is undoubtably the last bastion for the talentless. Hense the fact that U2 now seem to have become a tribute band to themselves.